DESICCATION TOLERANCE IN HIGHER-PLANTS RELATED TO FREE-RADICAL DEFENSES

Free radical-induced non-enzymatic peroxidation has the potential to d amage membranes, enzymes and nucleic acids and it is likely to be one of the major causes of injury during desiccation of higher plants. Pro tective mechanisms to scavenge the peroxidatively-produced free radica ls and peroxides have evolved within plants, keeping these deleterious compounds to a minimum. In this review the early intervention of glut athione, ascorbic acid and tocopherol is considered as a first line of defence to interrupt free radical action in membrane components. To c larify the link between plant desiccation tolerance and free radical d efences we have considered the changes in these major free radical red uctants and in membrane status in two resurrection plants, Boea hygros copica and Sporobolus stapfianus which offer the advantage that their leaves can exhibit desiccation tolerance depending on the manner in wh ich they are dehydrated.